Marking pen



FIG. 1 is a perspective view of a marking pen showing a right side of mynew design.

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

I claim the ornamental design for a marking pen, as shown and described.